** Shares of vaccine maker Moderna MRNA.O up 11% at $33.20

** On Monday, leading medical organizations filed a lawsuit against U.S. Health Secretary Robert F. Kennedy Jr. and Department of Health and Human Services, arguing that current policies on COVID-19 vaccines pose an imminent threat to public health

** B. Riley Securities analyst Mayank Mamtani said the share movement likely reflects "a reversal of peak negative investor sentiment, with now there being some near-term events, both vaccine advisory committee (VRBPAC) and lawsuit-related."

** Other vaccine makers like Pfizer PFE.N and Novavax NVAX.O up 1.6% and 6.7%, respectively

** Mamtani cites recent late-stage study data for COVID-influenza combination and standalone flu vaccines as an additional driver for NVAX stock

** Including sessions' moves, MRNA has lost 20.2% YTD, while NVAX is down 11.4%

(Reporting by Siddhi Mahatole)

((siddhi.mahatole@thomsonreuters.com))